#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>



int main() {

    double a, b, c, d, e, f;

    scanf("%lf %lf %lf %lf %lf", &a, &b, &c, &

        d, &e);

    f = (a + b + c + d + e) / 5;

    printf("%.2f", f);

    return 0;

}

